Longest Bitonic Subsequence
Detailed guide and Python implementation for the 'Longest Bitonic Subsequence' problem.
Problem Statement
Write a function lbs(arr) that returns the length of the longest bitonic subsequence in an array arr. A subsequence is bitonic if it first increases and then decreases, or strictly increases, or strictly decreases.
- •1 <= len(arr) <= 1000
- •-10^4 <= arr[i] <= 10^4
Examples
lbs([1, 11, 2, 10, 4, 5, 2, 1])
6
The longest bitonic subsequence is [1, 2, 10, 5, 2, 1] or [1, 2, 4, 5, 2, 1] with length 6.
lbs([12, 11, 40, 5, 3, 1])
5
The longest bitonic subsequence is [12, 11, 5, 3, 1] or [11, 40, 5, 3, 1] with length 5.
Need a Hint?
Edge Cases to Watch
- Empty input structures
- Single element inputs
- Large numerical bounds
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